Hello i masturbated alot from age of 11 or 12 now i am 17.now i feel my knee is hollow.when i masturbate ifeel pain in legs and knees and hardly walk.

No relationship: There is no relationship between how often you ejaculate (whether through sex or masturbation) and pains in extremities. You need to look for another reason for your leg symptoms, including psychological explanations, because it is not form your masturbation practices. Get this idea out of your head and move forward looking for another explanation.